Underneath it All
by ameliambrose
Summary: In his last year of college, Finn gets possessed by something old and evil. Four years later, he meets and falls in love with a fallen angel.


Finn always had an obsession with the supernatural.

When he was younger, he collected books on cryptids and had a huge handwritten encyclopedia of Americana folklore. He went out into the forest behind his home in Ireland looking for the Dobhar-chú and banshees, and kept books filled with notes about his findings and sightings, which may or may not have just been shadows that played tricks at the corner of his eyesight.

When he was a teenager, he moved to America with his parents. He went through a sudden, but fleeting gothic phase in high school and that was when he pulled demonology into his borderline obsession. He spent most of his free time reading about the various demons in all religions that offered them. Even when he went to college and abandoned the black nail polish and eyeliner, his dark fascination with the evil that lurked somewhere out there increased.

In his last year of college, Finn met a woman named Catrina at the library. She had approached him while his head was 10 pages deep in _Conjuring and Expelling Demons_ and struck up a conversation that, at the time, seemed innocent enough.

Finn was attracted to Catrina the same way he was attracted to demons. She had a certain smoky darkness that followed her wherever she went and Finn was drawn to it. Her dark hair, kohl rimmed eyes, and blood red lipstick haunted his dreams and sometimes, when he closed his eyes, all he saw was her face, her smile. He heard her laugh in the back of his mind at the most random times. When she told him to do something, he did it. When they finally had sex, he felt like he was burning from the inside out. She infected him with her control almost immediately after that and he should have known the infatuation he tripped and fell into wasn't natural.

They spent most of their free time exploring their fascinations with evil beings together. Finn's mind was so foggy with her that he didn't realize that his grades were failing, that he wasn't himself anymore, that she wasn't normal. In fact, Finn didn't notice that he was being used until the night Catrina brought him to some abandoned house miles away from campus. On the way there, she explained that it was time they tried to make contact with a demon and that she'd heard from a Demonologist friend that the particular house they were heading to was filled to the brim with supernatural entity. She told him that she loved him and wanted to experience it with him.

By then, Finn was under her influence completely and he ignored all of the red flags.

The house was old and the air around it thrummed with static. There was a _no stop turn back_ feeling that bled from the atmosphere, but Finn followed Catrina in. The walls on the inside of the house were covered with jagged languages that he couldn't understand and pictures of crosses and crying portraits of Jesus and Mother Mary.

Catrina made Finn sit in the middle of the room while she got to work, drawing pentagrams and chanting in a language that resembled Spanish, but it wasn't. It sounded twisted, heavy, and evil on her tongue and Finn felt afraid for the first time since he'd met her. Catrina began to call out for someone as she drew a knife from her bosom and sliced across the top of her breasts. Finn wanted to cry out to her, but everything felt heavy; his eyes, his tongue, his arms, his legs, the room... everything weight down on him.

The candles Catrina had lit went out suddenly and the room was filled with a heavy darkness. Even the moonlight stayed out as if it wouldn't dare disrupt the dark. Soon, a small light appeared above Catrina's head and a slick, red arm reached out of the darkness surrounding her to run its fingers through her hair. Finn couldn't believe what he was seeing. He felt nauseous, his stomach turning in fear and disbelief.

"Father, I have your offering." Catrina said, her voice shaky and exhausted. "I have your vessel."

A voice whispered to her in that same guttural language and it seemed to echo around the room, bouncing off the walls and caressing every inch of Finn's body.

"He is everything you asked for, and more. And he is no longer a virgin, like you asked." Catrina replied, her voice proud and happy under the hoarse tiredness.

Suddenly, Finn felt a hand on his face. He reached to touch the hand and he was met with an inky, stickiness, but no solid form. How was that possible?

"Don't be afraid, Finn." Catrina said. She was suddenly beside him. He could smell her perfume and feel the heat of her breath. "Let him in, and we will be together forever. Is that not what you wanted?"

The pain started from his heart and worked its way outwards. He felt like he was being filled with hot oil, like his veins were getting ready to burst. He screamed and he clawed at his skin and at his hair as he tried to get whatever it was that was making his body it's new home out. It felt like it went on for hours.

Suddenly, it stopped and he felt nothing. The pain ebbed away and he opened his eyes and saw the world as if he was seeing it for the first time. Catrina knelt before him in tears, surrounded by candles and dressed in white. Finn felt like he'd known her forever, since before she was born. Saw flashes of her birth and saw her being raised in a cult dedicated to him. Saw her partake in blood rituals and saw her get chosen by her cult to be the one to bring _him_ to their domain.

"Zasael," Catrina whispered as she touched his thigh gently. "Are you here with me, my love?"

Finn stared down at her for a moment before he turned and walked out of the house. Distantly he could hear Catrina screaming for him, he could hear the other demons and ghosts trapped in this rift between the worlds. He was simultaneously seeing and feeling the world as both Zasael and himself.

As he walked, he could hear a second pair of footsteps right after his own. Could feel hot breath at the back of his neck. He felt fingers lace with his own as he walked – no, _was lead_ – away from the house. The more he walked, the more he could feel the demon settle himself into his bones and in the back of his mind as he allowed Finn to take the reins. Finn became Finn again while Zasael took a back seat and just… watched.

* * *

After graduation, he stayed with his parents because he didn't trust himself to live on his own and they thought that he was suffering from deteriorating mental health so they accepted him willingly. His possession was not like in the movies. He did not hiss when he saw crosses and he didn't spew green vomit at everyone. He could even still go to church and pray which was surprising. Still, horrible things did happen that frightened him and his parents. Zasael wasn't dormant. Sometimes, he took over Finn's body and just did what he felt like doing. There were mornings when Finn would wake up covered in blood or would lose consciousness and regain it mid-thrust while hovering over a man or a woman that he'd never met before. One time, he tried to be normal again and went out to drink with friends and drank so much that he went home and passed out. When he woke up again, it was a month later and he was sitting in the middle of a burning pentagram in Mexico as naked cultists began to throw themselves into the fire.

The final straw came when his mother woke up in the middle of night to see him standing in the hallway, speaking to himself in a guttural language that she didn't understand as black and red tendrils came down from his head and a maw opened up from under his neck and called out for her.

His poor mother had a heart attack on the spot. Finn watched as Zasael laughed gleefully when she crumpled over and he could do nothing but hold on for the ride as Zasael slunk back into the shadows and relocated them to another city. He – they – crawled out of the shadows on all fours, slithering and dragging themselves as a woman on a bus stop saw them and began to scream. She ran and they chased her for a while, giving her an illusion of a fighting chance before they pounced on her.

Usually when Zasael took over, Finn was always unconscious. He didn't have to see the horrible deeds the demon did with his body, his likeness. But Zasael allowed him to see this time. It was like he wanted Finn to know that he couldn't pretend to have a normal life anymore.

Finn got the message that night. Loud and clear.

* * *

He'd been living with his demon for four years when he stumbled into a club and saw _him_.

Zasael liked clubs. Liked the darkness of the room and the thick, thumping bass while the bodies that were most likely in a drunken or drugged up state writhed around him. When he was around, the partygoers felt an abrupt urge to do _more_. They could feel his influence under their skin, but they didn't know the source. They'd go home and wake up next to some random stranger and chalk the night before up as wild time, not knowing that they had been manipulated for a demon's entertainment.

A room full of sin and fun was Zasael's haven and all of the men and women, with their dilated pupils and swiveling hips were his muses.

There was one man in particular, who seemed out of place in the crowd. He was the most beautiful person Finn and Zasael had ever seen. He was big and sharp; everything on his body was thick and imposing. He had the body and the stance of a fighter, a warrior. His light eyes trailed across the crowd in searching wonder as his lips turned up in a contrasting sneer.

He radiated something _light_. It was an otherworldly power, and it drew Finn in the same way Catrina's darkness pulled at him. He caught Zasael as well. There was something about this man that Zasael wanted to get his hands on and corrupt.

Finn didn't even notice that he'd moved until he was standing in front of the man. He was alone now; Zasael had disappeared to watch and observe as he counted on Finn to capture this man and bring him back to their motel.

"Hello," Finn said, his voice shaky and barely noticeable over the music. "Can I buy you a drink?"

"No, thank you," The man said before he turned abruptly and left, making his way to the entrance/exit door.

Finn followed him out of the club and in the back of his mind, he could feel Zasael pressing on him to _get him get him_.

"Hey, wait!" Finn called out as the man stormed off into the cold night air. "Leaving so soon?"

The man halted and Finn almost ran into his solid frame. He turned around to stare down at Finn with angry eyes, which still somehow radiated warmth.

"I know what you are," The man said as his eyes trailed Finn's body. His gaze stopped at Finn's chest and Finn suddenly felt warmth there. "Demon."

The words were hissed out and Finn stumbled back, afraid. How did this stranger know? Was he a demon too?

 _Angel._ Zasael provided from the back of his mind. _Archangel. Fallen, but still dangerous. Fallen, and therefore corruptible, just like humans. Want him. Must have him._

"I'm not a demon," Finn said lamely. He swallowed thickly, both afraid of and entranced by this being in front of him. "I'm a human. Just possessed."

"You're more than possessed, boy," The angel said. "You and the demon are entwined. One. I can't even see where he stops and you begin."

"You can see him?" Finn asked. "You can see us both?"

The angel didn't reply. Instead he folded his arms and regarded Finn slightly. "What do you want? I can't help you get rid of him."

"You're beautiful," Finn blurted, then caught himself. "I mean… shit…"

The angel stared at him for a long time before he smiled at him and Finn… Finn fell in love on the spot.

* * *

It was a weird and unlikely friendship. Roman told Finn that he liked him a lot and enjoyed his company, but he did not like Zasael, which was honestly expected. Roman was an _angel_. Fallen and disgraced, but still angelic and bright and beautiful and good. Too good, if Finn had to be completely honest, because he allowed Finn to be his friend, even if that mean having to put up with Zasael as well.

They were both happy to have someone that they could talk to. Finn didn't understand a lot about Roman's feeling of loss and emptiness from his fall, but he did sympathize with him and he was a willing ear for Roman when the other man just wanted to talk. And Roman helped with Zasael. Zasael was afraid of Roman at first. Didn't want to come out when Roman was around because of Roman's light. His ability to put the fear of God within Zasael was still there, even if he'd lost his halo.

The only thing that kept Zasael from forcing Finn to leave Roman behind was his hope that their relationship would continue to progress and that Roman would eventually commit the ultimate sin. It wasn't every day that an archangel, fallen or not, would fall in love a demon. A demon attached to a host, however, was a loophole, and Zasael intended on exploiting it.

* * *

The first time Roman kissed Finn, they were in Finn's shoddy motel room and he had just finished telling Roman about some of the cryptids he used to study when he was younger. Roman had looked at him as if he was an innocent, naive child, and nobody had looked at Finn like that in a long time. He hadn't felt innocent since his possession and the tenderness in Roman's gaze set Finn's heart on fire.

When Roman's lips touched against Finn's, he felt like the light that Roman had inside of himself poured into him and filled him up. He wasn't sure if the feeling was just all in his head or if it was real, if Roman's _essence_ was real, but his body buzzed as if he'd touched static.

Zasael was quiet, but he fed on the light hungrily and Finn wondered if he was pouring his darkness into Roman in return.

Finn traveled with him as they searched for Roman's fallen brother, the sole reason why Roman was on earth in the first place. They went down the east coast and then traveled along the south until they were in Arizona. For months, Zasael was quiet. No more whispers, no more fading sights of blood and sacrificial virgins, no more visions of fire and ashes underneath the Earth.

For the first time in a long time, Finn felt free. He felt undamned and Roman made him feel adored and loved. They spent their time together enjoying simply _human_ activities, including more kissing and touching. Nothing too heavy at first, because Roman was unaccustomed with human intimacy and Finn hadn't wanted to have sex with anyone while he was possessed, and the only times he did was when Zasael took control of him. But when Zasael retreated into the recess of his mind, Finn's suppressed libido returned with a vengeance as soon as he thought that he was finally alone again.

Their first time together was in the sweltering heat of Arizona, dead in the middle of Summer. They had just bought their tickets to Greece and Roman kept telling Finn how much he appreciated his company and how happy he was that he wasn't alone anymore. He kissed Finn as they got into bed together, naked as the day they were born, and pulled him close, ignoring the sweat that glossed his skin.

Finn rolled Roman over and touched him everywhere before he followed his fingers with his lips, worshipping the unbelievable span of perfect skin in front of him. He started at his chest, grazed his nipples with his tongue and his teeth, and he worked his way down his golden abs. Roman, who was always so calm and collected no matter what, had started breathing harshly through his nose. Finn kissed Roman's hipbones once and wrapped a tentative hand around his cock, causing the other man to hiss and buck.

Finn hoped nobody else ever got to see Roman like this. This was solely _his_. He prodded the back of his mind for Zasael, but he got no response, so he pressed on.

"If you feel… if you feel uncomfortable at any time," Finn said, almost breathless. "We can stop."

"I don't want to stop," Roman said as he ran a gentle hand through Finn's short hair. "I want to do this with you."

Finn smiled and moved up to kiss Roman gently before shifting down again. He stroked Roman's cock more firmly now, still shy, but less hesitant.

He wondered if this was sinning. Of course it was sinning. He was a possessed human male and Roman was a fallen angel. They had to have been committing several wrongdoings with these tender, loving motions. But when he looked up and caught Roman's eyes and the other man grinned at him, happy, overwhelmed, and bashful, Finn didn't care. How could he care about anything except making Roman happy?

He didn't hesitate once when he dipped his head down and took Roman in his mouth.

He couldn't fit all of him, but he tried his damnedest, and whatever he couldn't fit in his mouth, he stroked with his hand. Roman was extremely responsive, moaning and twitching and writhing against the rickety bed as Finn tried his best to make this amazing for him. He was shocked that someone like him… someone unworthy, could fill Roman with so much desire. It turned him on. Made him feel sexy and wanted. Made his own cock throb against the sheets as he pulled off and licked at Roman's glistening tip.

He spent some time figuring out what made Roman groan the loudest, what made him tighten his hand in Finn's hair before he eased off and gently pet him in apology, because even while he was getting a blowjob, he was still a gentle and kind soul.

Eventually, his work paid off when Roman tipped his head back against the pillows and filled Finn's mouth with thick, warm liquid. Finn choked, but he didn't let up. Wanted all of what Roman had to offer. He moaned through Roman's orgasm and only pulled off when Roman had begun to apologize profusely.

"It's ok," Finn said, after he'd swallowed everything Roman had given him. "I don't mind, it's ok."

Finn's body felt alight. He felt slightly dizzy as if he was tipsy, bordering on drunk. He felt holy, sanctified. He felt like all the darkness that had clung to his skin since he met Catrina years ago had been washed out and replaced with Roman's essence.

Roman kissed him again and they traded the tiny remnants of his come between their lips until there was nothing left. Roman turned aggressive, then. Pushed Finn back against the sheets before he even knew what was going on and covered his smaller body with his larger frame.

Sometimes Finn forgot that Roman was strong and dangerous. Not nearly as much as he used to be, but definitely one of the strongest and most powerful creatures that walked the Earth. The speed and strength that shifted Finn excited him and his legs fell open willingly, ready to take whatever Roman was willing to give him.

"You're beautiful," Roman whispered in awe as he stared at Finn. Stared right through him as if he was seeing Finn inside and out. "You're the most beautiful person I've ever seen."

Finn felt his eyes burn and his heart hammer in his chest. How could Roman think that? How was that possible when Roman could see the sleeping evil lurking under his skin?

"I love you," Roman said as he bent to kiss Finn's trembling lips. "Every part of you, even the darkness."

* * *

When they woke up the next morning, buried in each other's arms, Roman stroked his hair and just talked. He told Finn that he didn't remember what heaven looked like or what his Father sounded like anymore and that every day he forgot more of the divine language in fragments and soon, he'll only know human words. He told him that he envied humans and their ability to fail and still be forgiven. He told him that he'd never fallen in love with a human before, always thought that they were like spoiled children, but there in something in Finn that captivated him. He wondered aloud, seemingly more to himself than to Finn, if it was his possession and the fact that he remained so innocent despite being exposed to so much evil.

Finn stayed quiet during all of this, content to just lay there and listen. His mind swam with questions about everything. About Roman, about himself, about Zasael, about his religious beliefs, about heaven and hell and all in between… He didn't voice any of his concerns, though, because he was determined to be content, wrapped up in the arms of someone he loved.

When Finn woke up again, he had a front row seat to an argument between Zasael and Roman.

"Sweet, innocent Roman. Corrupted beyond repair," He – no, Zasael – taunted at Roman while the other man sat on the floor with his head in his hands. "I never thought that in my long life that I would bed an angel. An archangel at that. Who knew that you would be so easy? Who knew that you would taste to sweet. The corruption… it taints you now. Can you feel it?"

Roman's hands had begun to shake and glow, as if they were charging. Zasael jumped and clapped gleefully at the looming threat, taking more pleasure from that than the sadness and anger that fill the room. "Remember, remember: Kill me, kill him!" He sang. "Kill me, kill him!"

Finn suddenly got flashes of an all-out brawl that he'd missed while Zasael was in control of his body. He saw the anger on Roman's face and he felt the sick happiness that Zasael felt over Roman's sadness and lost temper. Just as Roman was about to end Zasael with a blow, the demon reminded him, with great joy, that Finn was trapped inside. Finn watched as Roman crumpled back against the wall and buried his face in his hands and that's where he found him when he woke up.

Roman looked distraught. He was crying, harsh ragged sounds that tore from his chest and echoed around the room. Finn realized then that that was why Zasael stayed away for so long. He waited for them to fall in love so he could get what he wanted. He knew that there would be no repercussions because Roman would never hurt him. Not while he shared a body with Finn.

Finn called out for Roman, but he was trapped inside his own mind while the demon pranced around in his body.

"I'll give you anything," Roman said quietly. "I'll do anything. Just please, give him back."

Zasael crouched down until he was eyelevel with Roman. "What exactly are you willing to do?"

"You want another vessel?" Roman asked, anxiously. "I'll get them. Anyone you want."

"Willing to damn another innocent so you can get your lover back?" Zasael sighed with mock disapproval. "Shame, shame. So selfish. Has your short time on earth already removed your vows and morals? They say love can turn the most just man wicked, but they never said the same about angels."

Roman stared at him defiantly and Finn felt his heart break. He was watching Roman's light ebb away slowly but surely and there was nothing he could do about it.

"Sodomy, wrath, selfishness, bargaining…" Zasael tsked and stood up. "Will you be willing to add murder to your list of sins if they meant I'd release your dare Finn?"

"I'd do anything," Roman repeated, voice still shaky. But he wasn't afraid. Finn could see that he wasn't afraid of Zasael and that made him happy.

Zasael laughed and it sounded horrible and twisted. "I guess I have truly ruined you. Too bad. Finn is mine. We are tied. We are one. There is no him without me."

Zasael began to slink into the shadows of the room and Finn cried out for Roman because he knew that when they stepped out into the light again, he and Zasael would be in another part of the world and Roman would be here alone again. He'd lost his brother, his halo, and now he was losing Finn.

"I'll find you," Roman said as he scrambled to stand up. "Finn if you can hear me, I will find you."

And then they were gone.

When Finn woke up again, he was on a beach, surrounded by bodies. Thankfully, everyone around him was still breathing, just fucked out and in a deep sleep. Still, he felt disgusted with himself. He felt hallow. Empty.

He missed Roman.

He rolled over and threw up until there was nothing else to come out.

 _Don't be sad, little one._ Zasael said from the back of his mind. _Eventually, we'll become one and the sight of darkness will no longer scare you._

Finn ignored him and stumbled to his feet. He decided then and there that this would go on no longer. Either he will exorcise Zasael or he will die trying.

* * *

 _ **by far the creepiest thing i've ever written. i had a lot of fun, but i'm also sad lol. thankfully, this will have a part two!**_


End file.
